OPX bid to raise $35 million in funding could get a cool reception from venture capitalists wary of the sector and the company's long timeline.

Building a chemical company from scratch requires substantial capital and presents major technology challenges. OPX Biotechnologies Inc. may be a test case of private investors' appetite for such risk.

More in Unleashing Innovation: Energy

OPX, which is developing a way to ferment sugars into chemicals as an alternative to using petroleum, recently hired investment bank Lazard Capital Markets to raise $35 million from investors. Although OPX is promising to bio-engineer microbes to produce chemicals that today are made out of petroleum—and do so at a competitive cost—Chief Executive Charles R. Eggert has said the company doesn't expect to generate any commercial revenue until at least 2017.

That is hard math for some investors. Venture capitalists eagerly backed companies developing biofuels and biochemicals in the mid-2000s, but they have earned little in return. Share prices for several such companies that went public in 2010 and 2011 have stayed below their initial offering price. Several other companies that planned to go public withdrew their offerings because of the unreceptive market.

Although venture investors have become more wary of the sector, Mr. Eggert says he hopes a winnowing of the market will lead to the best technologies attracting new interest. That could come from abroad, as foreign investors look to capitalize on the money already spent in the U.S. developing these technologies.

OPX previously raised $64 million in venture capital.

Solar Firm Makes a Shift

The company building the world's largest solar thermal power plant—with the help of $1.6 billion in government loans—is looking for more cash as it makes the transition from developing its own projects in the U.S. to providing technology for other solar companies, especially those located abroad.

BrightSource Energy Inc. of Oakland, Calif., which has about $615 million in backing from investors in addition to the government support, is scheduled to finish building Ivanpah, the solar thermal power plant in Nevada, later this year. The plant, partly owned by NRG Energy Inc.NRG0.40% and Google Inc., consists of three 459-foot-tall towers and 300,000 sun-reflecting mirrors and will be able to power 140,000 homes once completed, the company says.

As the Ivanpah project nears completion, BrightSource is increasingly looking away from the U.S. for business, signing memorandums of understanding to help develop large thermal projects in China.

Tim Keating of Keating Capital Inc., a BrightSource investor, says the planned $35 million funding round is aimed at sustaining the company as it shifts its business plan.

BrightSource declined to comment on its fundraising.

Prefab Homes Attract Boomers

The growing number of retiring baby boomers looking to move into smaller, more energy-efficient homes may be a boon for companies that make prefabricated houses, which are built in a factory and transported to a private lot.

Blu Homes Inc., a maker of prefabricated eco-friendly houses, recently raised $65 million from investors to buy land and put up model homes in about 10 target markets, including Los Angeles, the San Francisco Bay area, New York, Denver and Seattle, Chief Executive Bill Haney says.

Every day for the next 17 years or so, about 10,000 baby boomers will turn 65, according to the Pew Research Center. For some, the idea of picking a perfect spot for a retirement home and having a company bring them a house—usually more quickly and with fewer construction headaches than a typical home-building project—holds appeal, industry supporters say.

Blu Homes' average customer is 62 years old, Mr. Haney says.

The company expects sales of about $70 million this year, up from about $40 million in 2012, and plans to build about 120 homes this year.

Blu Homes and other prefab builders put a large emphasis on environmentally friendly features, including recycled materials, low-flow plumbing fixtures and energy-efficient lighting and appliances.

The company, founded in 2008, was valued at $400 million with the latest financing round, Mr. Haney says. Investors include Brightpath Capital Partners LP and Netherlands-based investment company Skagen Group.

Skyonic Corp. has closed on a $48 million Series C financing as it moves to build a commercial plant in San Antonio that will convert the carbon dioxide emitted by a cement plant into chemicals such as hydrochloric acid, baking soda and bleach. Investors include Energy Technology Ventures, which is a joint venture of General Electric Co.GE-0.08%, NRG Energy Inc. and ConocoPhillipsCOP-3.32%; and BP Ventures, the investment arm of oil-and-gas company BP PLC.

Write to Yuliya Chernova at yuliya.chernova@wsj.com. Follow her on Twitter at @ychernova.

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